System and method for operating a turbine-powered electrical generating plant in a sequential mode

ABSTRACT

A system and method for operating a turbine power plant wherein a feedforward steam flow demand signal governs the partial-arc or sequential operation of the steam-turbine inlet valves, is disclosed. Each valve control group is governed sequentially according to the individual valve percentage of total steam flow that such valve is required to admit. The total steam flow demand signal is dynamically calculated in accordance with a demand percentage of total flow capacity of the unit, the steam throttle pressure, the number of nozzles associated with each valve, and the effect of impulse chamber pressure. The steam inlet valves control the steam flow in the sequential mode throughout the range of steam flow demand by incrementally varying the valve lift positions within a predetermined operating range of steam flow. The valves of one group are fully open or closed only when such position permits the steam flow demand signal to control the sequentially adjacent valve group within the predetermined operating range. The extent to which the flow demand signal varies beyond the operating range of one valve group and below the predetermined operating range of the sequentially adjacent group determines the simultaneous direction of valve travel of adjacent valve groups, and which of the adjacent valve groups are controlling in the predetermined operating range. This range is varied with respect to the actual valve position in accordance with the total flow demand signal and the predetermined operating range is varied depending on the direction of steam flow demand change.

United States Patent i191 Ronnen 1 Apr. 15, 1975 [75] Inventor: Uri G. Ronnen, Monroeville, Pa.

[73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

[22] Filed: June 10, 1974 [21] Appl. No.: 478,815

Related U.S. Application Data [63] Continuation of Ser. No. 306,979, Nov. 15, 1972,

abandoned.

[52] U.S. Cl. 290/40; 235/l5l.2l; 444/1; 60/646 [51] Int. Cl...... G06j 1/00; G06f l5/O6; G06f 15/56 [58] Field of Search 235/l5l.2l, 151.34, 151.3, 235/151; 4l5/l,l3l4, 17; 60/646; 290/40 A40 C, 40 F; 444/1; 340/1725 OTHER PUBLICATIONS Application of the Prodac 50 System to Direct Digital Control; .1. C. Belz, G. J. Kirk & P. S. Radcliffe, IEEE Int]. Conv. Rec. Part 3, 1965; pp. 102-122. Monitoring and Automatic Control in Steam Power Stations by Process Computer; E. Doetsch & G. Hirschberg, Siemens Review XXXV(1968), No. 12; pp. 671-576.

Primary Examiner-Eugene G. Botz Assistant Examiner-Edward J Wise Attorney, Agent, or Firml-l. W. Patterson [5 7 ABSTRACT A system and method for operating a turbine power plant wherein a feedforward steam flow demand signal governs the partial-arc or sequential operation of the steam-turbine inlet valves, is disclosed. Each valve control group is governed sequentially according to the individual valve percentage of total steam flow that such valve is required to admit. The total steam flow demand signal is dynamically calculated in accordance with a demand percentage of total flow capacity of the unit, the steam throttle pressure, the number of nozzles associated with each valve, and the effect of impulse chamber pressure.

The steam inlet valves control the steam flow in the sequential mode throughout the range of steam flow demand by incrementally varying the valve lift positions within a predetermined operating range of steam flow. The valves of one group are fully open or closed only when such position permits the steam flow demand signal to control the sequentially adjacent valve group within the predetermined operating range. The extent to which the flow demand signal varies beyond the operating range of one valve group and below the predetermined operating range of the sequentially adjacent group determines the simultaneous direction of valve travel of adjacent valve groups, and which of the adjacent valve groups are controlling in the predetermined operating range. This range is varied with respect to the actual valve position in accordance with the total flow demand signal and the predetermined operating range is varied depending on the direction of steam flow demand change.

19 Claims, 45 Drawing Figures TTLE msssunsr DETECTOR lilo POWER n2 IMPULSE DETECTOR PRESSURE 9 DETECTOR STEAM LOAD TVI GVI 22 4 PDTI PDGI K 2 0mm TYPE BOILER STEAM M? [.F? L.F!

GENERATm g TURBINE TURBINE TURBINE GENERATOR svs'rzu I SECTION SECTION SECTION I l 1 2s 32 1 L1 Tv4 eve REHEATER I STEAM sv 1V CONDENSER I T-OGB L g POI ANALOG DlGlTAL 46 SPEED SPEED DETECTOR DETECTOR so ,52 HYDRAULIC i THROTTLE GOVERNOR Sv 58 59 s| N Fri Simon: ACTUATOR NTROLS ONTROLS E 42 44 l 48 image 'tititti VALV VALV ACT AT 5s ACTUATORS AcTuArgns 49 U 5 7 POSITION men PRESSURE CONTROLS HYDRAULIC FLUID SUPPLY FILTER SUPPLY I I SUMP L ,322

GH 32: P SSURE T L SUPPLY TO ACTUATORS a "f {In FILTER 4 SUMP 3 SUPPLY FIGB DEMODULATOR FILTER PATENTEDAPII I 5 I875 3. 8 7 8 4 U l SHEET 08 [1F 39 DATA PLANT COMMANDER PLANT wIRING L DATA TASK LINK INTERRUPT ERROR SEQEUEENCE OF v NTS 'Q LAMPS INTERRUPT "58M PROGRAM -vALvE II32 I852] INTERRUPT PLANT CCI SUBROUTINE REFERENCE I854 s [IMO STATUS DEMAND PANEL PANEL LOGIC LAMPS WINDOWS INTERRUPTJ TASK TASKS AND CONTACTS SPEED Y OPERATOR SELECTION 2008 |9|Q PANEL H56 TURBINE BUTTONS PROGRAM 2022 vALvE WP "30 (so .MANAGEMENT INTERRUPT \lsso R P2000 \20l8 THROTTLE CLOCK ERROR INTERRUPT 4 GOVERNOR 1 22 I4 I -IaI0 VALVES 1 AUXILIARY CONTROL I MONITOR HSYNCHRONIZER STOP TASK INITIAL TASK 1 52 1 I020 SPDLOOP H54 CARS. FRI??? 18.2 L FLASH POSITION TASK L CLOSE Gv H36 m ANALOG ScAN BREAKER II4I TASK OPEN INTERRUPT ATS U34 1 vISUAL BREAKER PLANT 'iffl INSTRUMENTATION H4 M ATS 0 PERIODICS lll8 CONTATTOLTJTPUTS 1 00 ATS H48 TEST ANALOG H TASK CONVERSION ANALOG I ROUTINE DISPLAY DIGITAL 1/ I W'NDOWS TREND TYPEWRITERS PROGRAMMER MESSAGE II44 WRITER CONSOLE TASK LOGGING TREND 8 TYPEWRITER RECORDER PATENTEDAPR 1 Bars 3 8 7 8 4 O l SHEET 0 7 BF 3 9 TABLE 1-1. TASK PRIORITY ASSIGNMENT FIG. 9

Core Level Function Frequency Location F STOP/INITIALIZE ON DEMAND 2F40 E AUXILIARY SYNCHRONIZER 0.1 SEC 14BD D CONTROL 1.0 SEC 2730 C OPERATORS PANEL ON DEMAND 2IBO B ANALOG SCAN 0.5 SEC 16D0 A ATS-PERIODICS 1.0 SEC 4420 9 LOGIC ON DEMAND 1962 8 VISUAL DISPLAY .10 SEC 11560 7 DATA LINK ON DEMAND SD10 6 ATS-ANALOG CONVERSIONS 5.0 SEC 6960 5 FLASH 0.5 SEC ISAO 4 PROGRAMMERS CONSOLE ON DEMAND 3000 3 ATS-MESSAGE WRITER 5.0 SEC 6CAO 2 ANALOG/DIGITAL TREND 1.0 SEC 31370 1 CCO TEST* ON DEMAND 0E80 0 BATCH PROCESSORS ON DEMAND 4000 *The CCO test task may be used only during maintenance and debugging periods, since this program overlays the data link progm area. "The batch processors may be used only on manual control and with the sync disabled; also,

the sequence of events interrupt mme disabled since the batch processor programs overlay the ATS program area.

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FLOW CHANGES 302 DURING A GV MODE TRANSFER COMPUTE TARGET COMPUTE TARGET FLOWS FOR FLOWS IN SEQ. MODE SINGLE MODE COMPUTE FLOW INCREMENTS AND NO. OF INCREMENTS NOCHGS=I FACT(I)=FTGT(I) DELF(I)=O v N TRFPG- NOVFOMO FALSE E YES COMPUTS FULLY OPEN VALVE PO m N AND UPDATE ONE VALVE A/O's ONLY (EXIT) (EXIT) g FIGZBB 

1. A system for operating a turbine power plant during a mode wherein a plurality of steam inlet valve means are operable successively in a predetermined sequence to effect variations in steam flow to the turbine comprising a steam turbine, a plurality of steam inlet valve means, each of which includes at least one steam inlet valve, control means for each valve means governed by a generated representation of valve lift position demand, means to generate a physical representation of total steam flow demand for the turbine, means to allocate successively portions of the total steam flow demand representation to respective ones of the plurality of valve means in the predetermined sequence so that allocated flows substantially equal the total steam flow demand, means governed by the total steam flow demand representation and the allocating means to generate for each valve means a representation of an allocated valve steam flow demand, said valve steam flow demand generating means being operative to govern the valve steam flow representations to correspond to a portion of the maximum flow capacity for sequentially operable valve means at times when the total turbine steam flow demand yet to be allocated is between predetermined flow values, and means governed by the generated allocated valve steam flow representations to generate respective valve lift position representations for the valve control means.
 2. A system according to claim 1 wherein one of the said predetermined flow values of the total turbine steam flow demand yet to be allocated is above a predetermined portion of the maximum flow capacity of one valve means and the other said predetermined flow value is below a predetermined portion of the maximum flow capacity for the sequentially operable adjacent valve means.
 3. A system according to claim 1 wherein said valve steam flow generating means is operative to generate a representation corresponding to a maximum flow capacity for one valve means at times only when the total turbine steam flow demand yet to be allocated is above a predetermined portion of the maximum flow value for the next sequentially operable valve means.
 4. A system according to claim 1 wherein the predetermined flow values of the total turbine steam flow demand yet to be allocated differs in accordance with the direction of total turbine steam flow change.
 5. A system for operating a turbine power plant during a mode wherein a plurality of steam inlet valve means are operated successively in a predetermined sequence to effect variations in steam flow, comprising: a steam turbine, a plurality of inlet valve means each operable to control steam flow to the turbine in accordance with their respective valve lift positions, control means for each valve mEans governed by a physical representation of valve lift position, means to generate a physical representation of turbine steam flow demand, means governed by the turbine steam flow demand representation to generate a physical representation of maximum steam flow each valve means is capable of admitting when fully open, means to store a physical representation of a predetermined flow value range of steam flow for each valve means, means governed by the difference between the turbine steam flow representation and generated allocated steam flow representations for each sequentially preceding valve means to generate a physical representation of unallocated turbine steam flow, allocating means governed by the stored physical representation and the representation of unallocated turbine steam flow and the representation of maximum valve flow to generate a physical representation of allocated valve steam flow for each of the valve means in succession, said physical representation of allocated valve steam flow for each valve means corresponding to either said maximum steam flow representation of said flow value range, and means governed by each of the allocated valve steam flow representations to generate said representations of valve lift position for each respective valve control means.
 6. A system according to claim 5 wherein the stored flow value operating range for each valve means is limited at one end by a low portion of maximum valve flow and at the other end by a high portion of maximum valve flow.
 7. A system according to claim 6 wherein the allocating means includes means to generate a first physical representation of an allocated valve steam flow for one valve means that corresponds to the difference between the unallocated steam flow representation for said one valve means and the low portion of maximum steam flow for the sequentially adjacent valve means, and to generate a second physical representation of allocated valve steam flow for the sequentially adjacent valve means that corresponds to said low portion of maximum flow at times when the unallocated steam flow for the one valve means is greater than said high portion of said one valve means and less than the sum of said high and low portions of maximum steam flow.
 8. A system according to claim 6 wherein the allocating means includes means to generate a first physical representation of allocated valve steam flow for one valve means that corresponds to the high portion and a second physical representation of allocated valve steam flow for a sequentially adjacent valve means that corresponds to the difference between the unallocated steam flow and the predetermined high portion for such one valve means at times when the unallocated steam flow is greater than the sum of the high portion for the one valve means and the low portion of the sequentially adjacent valve means but less than the maximum steam flow for the one valve means.
 9. A method of operating a steam turbine during a mode wherein a plurality of steam inlet valve means are operated successively in a predetermined sequence to effect variations in steam flow comprising: generating a representation of turbine steam flow demand, computing a maximum steam flow representation for each of a plurality of valve means in accordance with the turbine steam flow demand representation, computing an unallocated turbine steam flow representation for each of subsequent sequentially adjacent valve means in accordance with the turbine steam flow and a representation of target flow for each of the preceding sequentially operable adjacent valve means, comparing the representations of unallocated turbine steam flow and maximum steam flow and a representation of a predetermined operating range for each valve means to generate the representation of target flow, confining the target flow representations to a maximum flow or within predetermined operating range for predetermined ones of the plurality of valve means, generating a representation of valve lift position fOr each of the valve means in accordance with a respective target flow and turbine steam flow demand representation, and operating the valve means to a corresponding position in accordance with each respective valve lift position representation.
 10. A method according to claim 9 wherein the predetermined operating range for each valve means is limited by a low portion of maximum flow and a high portion of maximum flow, and further comprising generating a representation of target flow for each valve of two sequentially operable adjacent valve means corresponding to a portion of maximum flow within the limits of the operating range at times when the unallocated flow operable valve means is greater than the high portion of the predetermined range for one sequentially operable valve means and greater than the low portion of the other sequentially operable valve means.
 11. A method of operating a steam turbine generator system including a digital computer so as to operate a plurality of steam inlet valve means successively in a predetermined sequence in response to a steam flow demand representation, including a steam turbine, an electrical generator rotated by said turbine, a steam generating source for supplying steam to the turbine, a plurality of steam inlet valve means, each of which includes at least one inlet valve for controlling the flow of steam to the turbine, comprising the steps of: storing in the computer a physical representation of flow values defining the limits of a predetermined operating range for each valve means, operating the computer to generate a physical representation of the maximum flow capacity for each valve means in accordance with steam flow demand, operating the computer to allocate a portion of the total turbine steam flow representation to each one of the valve means in sequence until it substantially equals the total turbine steam flow demand representation, in accordance with the total turbine steam flow and a target flow representation for each preceding sequentially operable valve means, operating the computer to compare the maximum valve flow representation and flow value limit representations and the total turbine steam flow yet to be allocated to generate the target flow representation for each valve means, operating the computer to generate a representation of target flow for one valve means corresponding to the operating range at times when the unallocated portion of total turbine flow is greater than one stored flow value limit and less than the other stored flow value limit, and operating the plurality of valve means in accordance with the respective target values.
 12. A method according to claim 11, further comprising operating the computer to generate a representation of target flow for one valve means corresponding to one stored flow value limit at times when the total turbine steam flow yet to be allocated is greater than the sum of the stored flow value limits and less than the sum of the maximum flow capacity and the stored flow value limit of the lower end of the operating range.
 13. A method according to claim 12 further comprising operating the computer to generate a representation of target flow for one preceding sequentially operable means that is intermediate the flow value limits at times when the total turbine steam flow yet to be allocated is greater than the one stored limit value and less than the sum of both stored limit values.
 14. A system for operating a turbine powered generating plant during a mode when a plurality of steam inlet valves are operable in a predetermined sequence to effect variations in steam flow, comprising: an electric generator for producing an electrical load, a steam turbine for driving the generator, a steam generator for supplying steam under pressure to the turbine, a plurality of valve control means operable to control the flow of steam from the steam generator to the turbine in accordance with their respective valve lift positions, means for generating a signal representative of Load demand for the generator, means governed by the load demand signal for generating a representation of total turbine steam flow demand, a digital computer having a plurality of processing means for storing and calculating in a sequential manner, means in the computer to generate a physical representation of an allocation of a portion of total steam flow demand to respective ones of the plurality of valve means in the predetermined sequence so that allocated flows substantially equal the total turbine steam flow demand, said valve steam flow demand allocating means being operative to govern the valve steam flow representations to correspond to a portion of the maximum flow capacity for sequentially operable valve means at times when the total turbine steam flow demand yet to be allocated is between predetermined flow values, and means governed by the generated allocated valve steam flow representations to generate respective valve lift position representations for the valve control means.
 15. A system according to claim 14 wherein one of the said predetermined flow values of the total turbine steam flow demand yet to be allocated is above a predetermined portion of the maximum flow capacity of one valve means and the other said predetermined flow value is below a predetermined portion of the maximum flow capacity for the sequentially operable adjacent valve means.
 16. A system according to claim 15 wherein said valve steam flow generating means is operative to generate a representation corresponding to a maximum flow capacity for one valve means at times only when the total turbine steam flow demand yet to be allocated is above a predetermined portion of the maximum flow value for the next sequentially operable valve means.
 17. A system for controlling the operation of a turbine power plant wherein a plurality of steam inlet valve means are operable successively in a predetermined sequence in response to variations in steam flow demand, said system comprising, a steam turbine, an electric generator driven by the turbine, valve means for controlling the flow of steam to the turbine, valve control means for operating the valve means to control lift position in response to a physical representation, means for generating a representation corresponding to turbine steam flow demand, means responsive to the steam flow demand representation to allocate portions of the turbine steam flow representations to respective valve means in a predetermined sequence, said last named means being operative for two sequentially operative adjacent valve means to allocate a valve steam flow representation to correspond to portions of the maximum flow capacity of the valve means at times when the portion of the total steam flow demand for such valve means is sufficient to operate one valve means beyond a predetermined operating value and insufficient to operate the other valve means at a predetermined operating value when such one valve means is operated beyond such predetermined operating level, and means for applying the allocated steam flow physical values to respective valve control means.
 18. A system according to claim 17 wherein said last named means is operative to allocate a valve steam flow to one valve means that corresponds to a maximum flow level only at times when the steam flow demand portion for the next sequential valve means is above a predetermined operating level when the one valve is at maximum operating level.
 19. A system according to claim 17 wherein said last named means is operative to select one of two sequentially adjacent valve means to respond to a change in total steam flow when both such valve means are at an operating level corresponding to a portion of maximum flow in accordance with a total steam flow change that varies between a value above a predetermined operating value of one valve means and below a predetermined operating value of the other valve means. 